The Telecommunications Industry Association (TIA) Project 25 (P25) concerns a set of standards for digital radio communications for use by various groups including emergency response teams. P25 was established to address the need for common digital public safety radio communications standards, including push-to-talk (PTT) two-way radio communications standards.
P25 systems involve trunked radio communication. In a trunked radio communication network, a pool of available radio voice channels is maintained by a base station, and one or more radio control channels are used to assign a radio voice channel to a particular group of two-way radios from the pool as and when required. The radio voice channel is then returned to the pool upon completion of communication between the particular group of two-way radios.
All radios in a trunked radio communication network sometimes are not able to communicate effectively with the base station. For example, factors such as distance, transmitting power, and physical or geographic barriers may cause the radio of a specific subscriber unit to be able to receive control communications from a base station, but the subscriber unit is unable to successfully transmit control or other communications back to the base station. Mechanisms, including various proxy schemes and repeater elements, have been devised to improve the ability of individual radios in a network to communicate with the base station. However, such mechanisms often require additional network hardware, such as complex repeater systems.
Accordingly, there is a need for an improved method and apparatus for establishing radio communications on a trunked network.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.